A guide wire may include a core shaft and an external coil body covering a distal portion of the core shaft. The external coil body includes a first coil portion and a second coil portion that is distal to the first coil portion. An outside diameter of the second coil portion is smaller than an outside diameter of the first coil portion. Similarly, the guide wire may include a core shaft, a first external coil body, and a second external coil body. An outside diameter of the second external coil body is smaller than an outside diameter of the first external coil body. The external coil body or first and second external coil bodies enable the performance of a pushing-out operation and a drawing-in operation of the stent yet, the flexibility of the guide wire is maintained.